DHN 311 EXAM 1 QUESTIONS WITH
100% CORRECT ANSWERS
How does temperature impact enzyme velocity? - Answer-increasing temps=increased
velocity
How does pH impact enzyme velocity? - Answer-can increase or decrease the velocity
depending on the enzyme
-denaturation can occur
(Before or After) ______ Vmax is reached, there is free enzyme available for the
substrate to bind. - Answer-before
When substrate concentration is ______ (low or high) there is plenty of free enzyme
available.Which means that when enzyme and substrate come together the velocity of
the reaction quickly increases, indicating the rate of the reaction is dependent on
substrate concentration - Answer-high
The ______ curve is the curve that forms between the points of the reaction where the
reaction velocity moves rapidly with enzyme binding to substrate to the end of the
reaction where all of the free enzyme is bound to substrate and the reaction velocity has
leveled off - Answer-hyperbolic
Once Vmax has been reached this indicates that the reaction has leveled off because
all of the available enzyme is bound to substrate. So adding substrate at this point of the
reaction would not affect the rate of the reaction because the substrate would have no
enzyme to bind to. But adding enzyme to the reaction at this time will ______ (increase
or decrease) Vmax because free enzyme has been added to the reaction which
available substrate can now bind - Answer-increase
Km measures _______, not a velocity - Answer-concentration
An increase in Km indicates that ____ substrate is required for an enzyme to bind
substrate. - Answer-more
Km is the concentration of substrate which permits the enzyme to achieve half _____ -
Answer-vmax
____ is inversely related to the affinity of the enzyme for its substrate. In other words,
high values of Km correspond to low enzyme affinity for a substrate because it takes
, more substrate to get to Vmax. Low values of Km correspond to an enzyme with high
affinity for a substrate. It takes less substrate for an enzyme to reach Vmax. Enzymes
can be altered to increase or decrease their affinity for a substrate as is the case with
allosteric enzymes - Answer-Km
The ______ plot is the inverse of the Km and Vmax of a reaction. It turns the MM curve
into a straight line. Visually this makes it easier to see if Km, Vmax or both has been
altered once enzyme inhibition enters the picture. - Answer-Lineweaver-burk
Vmax (is affected or not affected) _________ at sufficiently high substrate concentration
in the situation of competitive inhibition. This is because the inhibitor concentration is
fixed and cannot compete with an increase in substrate. The amount of enzyme has not
changed and the enzyme itself has not changed, but the substrate concentration has
increase. The rate of the reaction to get to Vmax is slower, but the substrate
concentration required to saturate the enzyme (Vmax) has not changed with competitive
inhibition. Do not confuse the velocity of the reaction and Vmax. These terms are
different and not interchangeable. - Answer-not affected
Km ________ (increases or decreases) with a competitive inhibitor. In the presence of a
competitive inhibitor more substrate is needed to achieve ½ Vmax. This is because the
substrate is competing with the inhibitor to bind to the enzyme. The competition is
creating a binding problem. When it is difficult for an enzyme and substrate to bind the
affinity of an enzyme for its substrate is decreasing - Answer-increases
A non-competitive inhibitor ________ (competes or does not compete) with the
substrate to bind the enzyme? - Answer-does not compete
The Lineweaver Burk plot indicates a competitive inhibitor is the culprit because the Km
changes while the ______ remains the same. You know that the Km changes because
the lines on the x-axis of the Lineweaver Burk plot do not come together, which
indicates the Km between the competitive inhibitor and no inhibitor are not the same.
The Vmax on the other hand is the same as indicated by the competitive inhibitor and
no inhibitor lines coming together at the same point on the y-axis. - Answer-Vmax
Since the ability of the substrate to bind to the enzyme may not change in the situation
of non-competitive inhibition, Km ______ (increases, decreases or does not change) -
Answer-does not change
Vmax ______ (decreases, increases, or no change) in the situation of a non-competitive
inhibitor? This makes sense because when a non-competitive inhibitor binds it changes
the active site and makes the enzyme less effective when the substrate is bound to it.
What it comes down to is essentially less enzyme being available for substrates to bind
and effectively work when substrate is bound to it. When the concentration of enzyme
either increases or decreases it is a Vmax issue. Binding problems are associated with
Km. - Answer-decreases
100% CORRECT ANSWERS
How does temperature impact enzyme velocity? - Answer-increasing temps=increased
velocity
How does pH impact enzyme velocity? - Answer-can increase or decrease the velocity
depending on the enzyme
-denaturation can occur
(Before or After) ______ Vmax is reached, there is free enzyme available for the
substrate to bind. - Answer-before
When substrate concentration is ______ (low or high) there is plenty of free enzyme
available.Which means that when enzyme and substrate come together the velocity of
the reaction quickly increases, indicating the rate of the reaction is dependent on
substrate concentration - Answer-high
The ______ curve is the curve that forms between the points of the reaction where the
reaction velocity moves rapidly with enzyme binding to substrate to the end of the
reaction where all of the free enzyme is bound to substrate and the reaction velocity has
leveled off - Answer-hyperbolic
Once Vmax has been reached this indicates that the reaction has leveled off because
all of the available enzyme is bound to substrate. So adding substrate at this point of the
reaction would not affect the rate of the reaction because the substrate would have no
enzyme to bind to. But adding enzyme to the reaction at this time will ______ (increase
or decrease) Vmax because free enzyme has been added to the reaction which
available substrate can now bind - Answer-increase
Km measures _______, not a velocity - Answer-concentration
An increase in Km indicates that ____ substrate is required for an enzyme to bind
substrate. - Answer-more
Km is the concentration of substrate which permits the enzyme to achieve half _____ -
Answer-vmax
____ is inversely related to the affinity of the enzyme for its substrate. In other words,
high values of Km correspond to low enzyme affinity for a substrate because it takes
, more substrate to get to Vmax. Low values of Km correspond to an enzyme with high
affinity for a substrate. It takes less substrate for an enzyme to reach Vmax. Enzymes
can be altered to increase or decrease their affinity for a substrate as is the case with
allosteric enzymes - Answer-Km
The ______ plot is the inverse of the Km and Vmax of a reaction. It turns the MM curve
into a straight line. Visually this makes it easier to see if Km, Vmax or both has been
altered once enzyme inhibition enters the picture. - Answer-Lineweaver-burk
Vmax (is affected or not affected) _________ at sufficiently high substrate concentration
in the situation of competitive inhibition. This is because the inhibitor concentration is
fixed and cannot compete with an increase in substrate. The amount of enzyme has not
changed and the enzyme itself has not changed, but the substrate concentration has
increase. The rate of the reaction to get to Vmax is slower, but the substrate
concentration required to saturate the enzyme (Vmax) has not changed with competitive
inhibition. Do not confuse the velocity of the reaction and Vmax. These terms are
different and not interchangeable. - Answer-not affected
Km ________ (increases or decreases) with a competitive inhibitor. In the presence of a
competitive inhibitor more substrate is needed to achieve ½ Vmax. This is because the
substrate is competing with the inhibitor to bind to the enzyme. The competition is
creating a binding problem. When it is difficult for an enzyme and substrate to bind the
affinity of an enzyme for its substrate is decreasing - Answer-increases
A non-competitive inhibitor ________ (competes or does not compete) with the
substrate to bind the enzyme? - Answer-does not compete
The Lineweaver Burk plot indicates a competitive inhibitor is the culprit because the Km
changes while the ______ remains the same. You know that the Km changes because
the lines on the x-axis of the Lineweaver Burk plot do not come together, which
indicates the Km between the competitive inhibitor and no inhibitor are not the same.
The Vmax on the other hand is the same as indicated by the competitive inhibitor and
no inhibitor lines coming together at the same point on the y-axis. - Answer-Vmax
Since the ability of the substrate to bind to the enzyme may not change in the situation
of non-competitive inhibition, Km ______ (increases, decreases or does not change) -
Answer-does not change
Vmax ______ (decreases, increases, or no change) in the situation of a non-competitive
inhibitor? This makes sense because when a non-competitive inhibitor binds it changes
the active site and makes the enzyme less effective when the substrate is bound to it.
What it comes down to is essentially less enzyme being available for substrates to bind
and effectively work when substrate is bound to it. When the concentration of enzyme
either increases or decreases it is a Vmax issue. Binding problems are associated with
Km. - Answer-decreases
